Project Abstract Preterm birth affects approximately one out of every ten infants born in the United States, resulting in significant neonatal and life-long morbidities and economic costs. Preterm infants are at risk for developing a number of psychiatric disorders, including attention-deficit hyperactivity disorder (ADHD). Although a substantial body of work supports the association between preterm birth and ADHD, there is a critical need for a better understanding of the specific risk factors and mechanisms that link preterm birth to ADHD and its related developmental, neurocognitive, and socioemotional deficits. Preterm infants commonly endure neonatal morbidities (i.e., intraventricular hemorrhage [IVH], bronchopulmonary dysplasia [BPD], and patent ductus arteriosus [PDA]) that may be important predictors of risk for ADHD, yet work has not examined variability in neonatal morbidities and potential connections to ADHD and related deficits. Such research is essential to explicating the specific risk factors and mechanisms underlying the association between preterm birth and ADHD. The proposed research will determine whether specific neonatal morbidities (i.e., IVH, BPD, and PDA) are associated with ADHD-relevant developmental delays in early childhood (30 months of age) by utilizing an archival database from the University of Iowa High Risk Infant Follow-up Clinic. Further, the archival database will be used to identify preterm children (ages 6-10 years) for recruitment to a follow-up study examining neurocognition, socio-emotional processes, and ADHD symptomology. Neurocognition and socio- emotional processes at 6-10 years of age will be examined as mediators of the association between preterm birth and ADHD symptoms. The long-term objective of this research is to provide a better understanding of the mechanisms underlying links between preterm birth and ADHD, with the goal of improving prevention and intervention efforts. Notably, the complementary goals of this research and training plan, including gaining knowledge about neonatal morbidities and typical development and enhancing skills related to scientific writing, statistical analyses, and clinical assessment, will provide the applicant with a strong foundation for becoming an independent clinical scientist.